The first couple of trials and the last trial are the hardest bits. For the first few, the enemy stats are frankly, absurd, and the odd assortment of classes are a bit of a headache to go around unless you look up the enemy setup. The middle set isn't that bad, considering two of them contain Rulers which suddenly makes Avenger actually useful and your choice of class more focused.
Still working on the last trial, because gah the boss ghost.